Blank for easily opened box and the box formed from such blank

Abstract

A box blank can be used for American boxes (10), the main flaps (20, 20', 22, 22') of which have dimensions practically equal to the opening of the box and which are glued to each other to close this box. The outer top flap (20) has a perforation (30) located in the vicinity of the fold and the inner top flap (22) has a first cutout (40) adapted so as not to interfere with the pressing down of the middle part (36) of the perforation (30) during the opening of the box, and a second cutouts (42, 44) adapted so as not to interfere with the tearing off of the outer top flap 20 when the box is opened completely.

We claim: 
     
       1. A blank for a cardboard box, of length L, width l and height h, having a main part, the length of which is substantially equal to 2(L+l) and the width of which is equal to the height h of the box, and which is provided with folding lines so as to enable the blank to be folded to form the box, the main part being equipped, at one end which has a dimension equal to the height, with a tab (16) designed to be glued to another end (16') of the main part so that this main part, after the gluing and folding of the blank along the folding lines disposed transversely on this main part, defines the four vertical walls of the box, two lateral walls (14, 14') of length L and height h, and a front wall (12) and rear wall (12') of length L and height h, and two series of four flaps disposed on each side of the main part to form, respectively, the bottom and top of the box, each series of flaps comprising two lateral flaps (24, 26, 24', 26') with a general shape that is substantially square and an outer and inner flap (20, 22, 20', 22') each having a surface covering substantially the whole of the surface of the bottom or top of the box, once the latter has been formed, characterised in that: a) the outer top flap (20), joined to the top of the box, has a perforation (30) in three parts, two substantially symmetrical outer parts (32, 34) defining arcs of a circle having substantially the same centre and disposed in the vicinity of the folding line between the outer top flap and the main part, and a middle part (36), a convex side of which faces in an opposite direction to a convex side of the two outer parts, the distance between the points on the outer parts of the perforation and the folding line increasing progressively with the distance from the middle part along this perforation,   b) the inner top flap (22), joined to the top of the box, has, on its outer edge, opposite the folding line between the inner top flap and the main part, a first shape (40) adapted to the middle part of the perforation so as to slightly interfere with the pressing down of the part of the outer top flap defined by the middle part of the perforation during the opening of the box, and a second shape (42, 44) adapted to the two outer parts of the perforation so as to slightly interfere with the tearing off of the outer top flap during the opening of the box.   
     
     
       2. A blank according to claim 1, for the production of a box, the length L of which is less than twice the width l of this box, in which at least one of the top lateral flaps and at least one of the bottom lateral flaps has a width which is less than the width of the box and characterised in that the corner of each of the two lateral top flaps opposite the inner top flap and the corresponding folding line connecting this flap to the corresponding lateral vertical wall of the box, is cut out in such a way as to free the area located opposite the middle part of the perforation when the box is closed in order not to interfere with the pressing down of the part of the outer top flap defined by the middle part of the perforation during the opening of the box. 
     
     
       3. A blank according to claim 1, in which the middle part of the perforation is practically a semi-circle. 
     
     
       4. A blank according to claim 1, in which the first shape is a semi-circular cutout. 
     
     
       5. A blank according to claim 1, in which the second shape consists of two linear sloping parts connecting the first shape to the sides of the inner top flap which are adjacent to the lateral walls of the box so that the dimension of the inner top flap at the level of these sides is approximately equal to the distance separating the ends of the perforation of the side of the outer top flap opposite the folding line connecting the said outer top flap to the corresponding vertical wall of the box. 
     
     
       6. A blank according to claim 1, for producing a corrugated cardboard box of the 2.4 BE type, characterised in that the perforation comprises a succession of cut sections alternating with uncut sections, the cut sections having a length which is double that of the uncut sections. 
     
     
       7. A blank according to claim 6, in which the arcs of circles defining the outer parts of the perforation have a radius of less than 35 cm. 
     
     
       8. A blank according to claim 6, in which the sections of the outer parts of the perforation located in the vicinity of the middle part are separated by a distance of about 6 cm. 
     
     
       9. A blank according to claim 6, in which the perforation ends about 4 cm from the lateral walls of the box. 
     
     
       10. A cardboard box formed from a blank having length L, width l and height h, and having a main part, the length of which is substantially equal to 2(L+l) and the width of which is equal to the height h of the box, and which is provided with folding lines so as to enable the blank to be folded to form the box, the main part being equipped, at one end which has a dimension equal to the height, with a tab (16) designed to be glued to another end (16') of the main part so that this main part, after the gluing and folding of the blank along the folding lines disposed transversely on this main part, defines the four vertical walls of the box, two lateral walls (14, 14') of length L and height h, and a front wall (12) and rear wall (12') of length L and height h, and two series of four flaps disposed on each side of the main part to form, respectively, the bottom and top of the box, each series of flaps comprising two lateral flaps (24, 26, 24', 26') with a general shape that is substantially square and an outer and inner flap (20, 22, 20', 22') each having a surface covering substantially the whole of the surface of the bottom or top of the box, once the latter has been formed, characterized in that: a) the outer top flap (20), joined to the top of the box, has a perforation (30) in three parts, two substantially symmetrical outer parts (32, 34) defining arcs of a circle having substantially the same centre and disposed in the vicinity of the folding line between the outer top flap and the main part, and a middle part (36), a convex side of which faces in an opposite direction to a convex side of the two outer parts, the distance between the points on the outer parts of the perforation and the folding line increasing progressively with the distance from the middle part along this perforation,   b) the inner top flap (22), joined to the top of the box, has, on its outer edge, opposite the folding line between the inner top flap and the main part, a first shape (40) adapted to the middle part of the perforation so as to slightly interfere with the pressing down of the part of the outer top flap defined by the middle part of the perforation during the opening of the box, and a second shape (42, 44) adapted to the two outer parts of the perforation so as to slightly interfere with the tearing off of the outer top flap during the opening of the box.   
     
     
       11. A box according to claim 10, for the production of a box, the length L of which is less than twice the width l of this box, in which at least one of the top lateral flaps and at least one of the bottom lateral flaps has a width which is less than the width of the box and characterised in that the corner of each of the two lateral top flaps opposite the inner top flap and the corresponding folding line connecting this flap to the corresponding lateral vertical wall of the box, is cut out in such a way as to free the area located opposite the middle part of the perforation when the box is closed in order not to interfere with the pressing down of the part of the outer top flap defined by the middle part of the perforation during the opening of the box. 
     
     
       12. A box according to claim 10, in which the middle part of the perforation is practically a semi-circle. 
     
     
       13. A box according to claim 10, in which the first shape is a semi-circular cutout. 
     
     
       14. A box according to claim 10, in which the second shape consists of two linear sloping parts connecting the first shape to the sides of the inner top flap which are adjacent to the lateral walls of the box so that the dimension of the inner top flap at the level of these sides is approximately equal to the distance separating the ends of the perforation of the side of the outer top flap opposite the folding line connecting the said outer top flap to the corresponding vertical wall of the box. 
     
     
       15. A box according to claim 10, for producing a corrugated cardboard box of the 2.4 BE type, characterised in that the perforation comprises a succession of cut sections alternating with uncut sections, the cut sections having a length which is double that of the uncut sections. 
     
     
       16. A box according to claim 15, in which the arcs of circles defining the outer parts of the perforation have a radius of less than 35 cm. 
     
     
       17. A box according to claim 15, in which the sections of the outer parts of the perforation located in the vicinity of the middle part are separated by a distance of about 6 cm. 
     
     
       18. A box according to claim 15, in which the perforation ends about 4 cm from the lateral walls of the box.